From Pathfinder Guns & Gears, which isn't enabled.

Gigaton Strike

FEAT 8

When you use a full-power Megaton Strike, you can knock your foe back. When you succeed at your Strike while using an unstable Megaton Strike, your target must attempt a Fortitude save against your class DC.

Critical Success The creature is unaffected.

Success The creature is pushed back 5 feet.

Failure The creature is pushed back 10 feet.

Critical Failure The creature is pushed back 20 feet.

Special If your innovation is a minion, this benefit applies on its unstable Megaton Strikes.

Pathfinder Guns & GearsORC